Improving microstructure of silicon/carbon nanofiber composites as a Li battery anode

► We report an interfacial study of a silicon/carbon nanofiber (Si/CNF) anode for Li-ion batteries. ► Amorphous Si layers were uniformly coated on both the exterior and interior walls of the hollow CNF. ► After cycling, more Si had fallen off from the outer wall than from the inner wall of CNF. ► Computer modeling suggests a higher interfacial strength at the Si/C interface at the inner wall. ► We proposed several interfacial engineering approaches to optimize the microstructure.